Devices (that is, computer peripherals such as printers, cameras, external storage, and the like) may be connected to a computer using various types of standard connections, one of which is the so-called USB (Universal Serial Bus).
The USB system/standard was designed and intended to support computer peripherals that are physically close to the computer—mostly these devices are expected to be located on the same desk as the computer itself or within the same room as the computer. The USB system is defined by a formal specification, the current version of which is USB 2.0 (dated Apr. 27, 2000), the entire contents of which are incorporated herein by reference. Under the USB 2.0 Specification, the maximum distance from a port on a computer (a so-called root port) to any supported device is thirty meters and is achieved, for example, using a series arrangement of five hubs and six five-meter cable segments.
The inventor has found that for certain applications, however, it necessary or desirable to enable USB functionality at distances greater than thirty meters. For certain applications, USB functionality is desired at distances of at least one hundred meters and preferably at distances of seven hundred and fifty meters or more (for copper and fiber link products respectively).
For example, in a KVM (“Keyboard, Video, Mouse”) system, a target or host computer may be controlled and accessed by peripheral devices (possibly connected to another computer) that are possibly located some distance away from the target computer. In such cases, it is desirable to be able to connect all kinds of peripheral devices, including USB devices, to the host computer.
Thus, in at least one aspect, the present invention provides a USB system/extension that allows for the transmission of data over greater distances than contemplated by the USB standard.